As far as I know these body threshold trim plates were never factory issue but could have been common dealer installed accessory parts. Since the body sill (outer rocker panel in particular) is tapered front to back, the one pictured is a right side part, wider on the right (front) end with a small downward flange on the outer edge. These could have been available from several aftermarket parts suppliers such as Amco and MG Mitten, as well as over the parts counter at your local MG dealer. They are still available today as new aftermarket parts.

Theshold plates are commonly made of brushed or polished aluminum, but might also have been chrome plated steel (on rare occasion). They usually have ridges that serve well to comaflage scuffs and scratch marks. Some may have a large MG emblem embossed in the center facing outward. They are most often held in place by two grommet head trim screws (see holes in picture). The preceeding page shows interior frame rail covers that are often used in conjunction with the threshold plates.